The invention relates in general to coke ovens and in particular to a new and useful device for sealing the chambers of coke ovens in the range of the oven roof above the doors at the transition from the silica brickwork to the fireclay brickwork.
In today's conventional construction of coke ovens, the brickwork of the oven chambers consists mostly of silica bricks, which show a favorable low expansion behavior at the normal application temperatures of 1000.degree. to 1400.degree. C. Above the oven chambers proper no silica material is used anymore in the range of the oven roof, and particularly at the port ends, because of the great temperature fluctuations and the altogether much lower temperatures, since it would no longer withstand the alternating stresses. Instead fireclay material is used as a rule, which is much better and cheaper for the low temperatures prevailing in the range of the roof and of the upper port ends. But as it can be seen particularly for the thermal expansion curves (see Grossinsky, Handbuch des Kokereiwesens, vol. 1, Dusseldorf 1965, p. 228 ff) the elongation is different in the two materials. Silica material shows at the temperatures appearing in the coke ovens an about 0.7% higher thermal expansion than fireclay material. This fact is already taken into account in the construction of coke ovens by providing a so-called "silica rebound" relative to the fireclay brickwork, which is normally compensated during the heating up of the ovens by the different elongation. But it cannot be prevented in practice that cracks and open joints appear with this different expansion behavior in the fireclay brickwork with its lesser expansion applied on the silica brickwork, due to the greater expansion of the silica bricks. Attempts have been made to prevent possible leaks with the resulting later gas emissions during the heating by the application of tie rods and by subsequent closing of the openings by casting.
A particularly critical point at which emission of the crude gases occur, again and again during the operation, is at the silica-fireclay boundary in the range of the port ends above the door frame, where the greatest displacement of the two brick materials relative to each other takes place in a horizontal direction. On the other hand, the brickwork grows at this point by more than 1% in the vertical direction relative to the door frame in front of it with the armor, which are already inserted into the brickwork in the cold state, and relative to the bricks arranged directly above the frame.
The sealing of the brickwork from the outside was effected heretofore only by a protective wall plate which is arranged vertically above the frame in front of the brickwork. The oven is thus covered neatly from the outside, but leaks may be caused in the inner refractory region by the displacement of the brickwork in at least two directions. The result is that the points at which crude gases can escape from the oven block are difficult to seal because it is difficult to get to the points inside the oven. Besides, the protective wall plates as a connection between two buckstays extend from one heating wall to the other, so that the brickwork surfaces that cannot be reached from the outside are rather large.
It is also frequently necessary to correct the position of these protective wall plates during the heating period, because they slip up during the displacement of the brickwork parts or do not remain exactly in a vertical position. Irregularities in the brickwork like oblique bricks or cavities cannot be eliminated, however.
In order to avoid the problems of the different expansion during heating, it has been frequently tried to brick up a part of the roof brickwork, particularly at the ports above the door frame, only after the main expansion of the brick material is completed. But this involves additional difficulties, because the bricks, which have been inserted cold, are easily destroyed by the temperature shock and because the working conditions on the hot oven battery are much less favorable. Besides, the subsequent installation of the bricks considerably delays the further construction and assembly work.
From U.S. Pat. No. 1,029,798 are known port linings for the walls of horizontal chamber ovens where iron protective wall plates are provided between the buckstays and the oven brickwork, and tin plates less brick layers are arranged one above the other between the oven brickwork and the protective wall plates or frame wings, which are secured on the brickwork by pins protruding into the brick joints. These tin plates facilitates only a sliding motion in a vertical direction between protective wall plate and brickwork, but provide no gastight seal. With different expansions in horizontal direction, such a sliding motion is hindered causing the above mentioned cracks in the brickwork.